Apparatus and methods for the continuous measurement of specific gravity or density of solids in a fluid medium are disclosed. A system for continuous measurement of density of a flowing medium comprises a cartridge connected in series to an inflow pipe and an outflow pipe, a displacement sensing device adapted to monitor displacement changes of the cartridge when a medium flows through the cartridge, a base configured to provide a support for the displacement sensing device, a pressure sensor, a temperature sensor, and a processor configured to calculate density of the flowing media based on measured displacement change, temperature and pressure.
